BiPo prototype for SuperNEMO radiopurity measurements

TL;DR

The paper presents the BiPo prototype designed for ultra-sensitive radiopurity measurements of SuperNEMO source foils, focusing on background studies and preliminary sensitivity results in detecting trace radioactive contaminants.

Contribution

It introduces a modular BiPo1 prototype for measuring extremely low levels of radioactivity in beta-beta source foils, advancing radiopurity detection techniques.

Findings

Preliminary upper limit on 208Tl contamination: <7.5 microBq/kg

Prototype has 20 modules and operates in an underground lab

Initial background studies inform future sensitivity improvements

Abstract

The BiPo project is dedicated to the measurement of extremely low radioactive contaminations of SuperNEMO beta-beta source foils (208Tl < 2 microBq/kg and 214Bi < 10 microBq/kg). A modular BiPo1 prototype with its 20 modules and its shielding test facility is running in the Modane Underground Laboratory since February, 2008. The goal of this prototype is to study the backgrounds and particularly the surface contamination of plastic scintillators. After 2 months, a preliminary upper limit on the sensitivity of a 10 m2 BiPo detector in 208Tl contamination of selenium source foils can be extrapolated to: A(208Tl) < 7.5 microBq/kg (90 % C.L.).